Aragorn arrays the Host of the West on the Slag-hills

The two vast iron doors of the Black Gate... were fast closed. Upon the battlement nothing could be seen. All was silent but watchful. They... stood forlorn and chill... before towers and walls which their army could not assault with hope.... Yet they knew that all the hills and rocks about the Morannon were filled with hidden foes, and the shadowy defile beyond was bored and tunnelled by teeming broods of evil things. And as they stood they saw all the Nazgûl gathered together, hovering above the Towers of the Teeth like vultures; and they knew that they were watched. But still the Enemy made no sign.

No choice was left them but to play their part to its end. Therefore Aragorn now set the host in such array as could best be contrived; and they were drawn up on two great hills of blasted stone and earth that orcs had piled in years of labour. Before them towards Mordor lay like a moat a great mire of reeking mud and foul-smelling pools.

The Return of the King, LoTR Book 5, Ch 10, The Black Gate Opens

Upon the one hill [Aragorn] stood with Gandalf, and there fair and desperate was raised the banner of the Tree and Stars. Upon the other hill hard by stood the banners of Rohan and Dol Amroth.... And about each hill a ring was made facing all ways, bristling with spear and sword. But in the front towards Mordor where the first bitter assault would come there stood the sons of Elrond on the left with the Dúnedain about them, and on the right the Prince Imrahil with the men of Dol Amroth tall and fair, and picked men of the Tower of Guard.

The Return of the King, LoTR Book 5, Ch 10, The Black Gate Opens

[Pippin] stood beside Beregond in the front rank of Gondor with Imrahil's men. For it seemed best to him to die soon and leave the bitter story of his life, since all was in ruin.